/Engine/Source/Runtime/SlateCore/Public/Input/HittestGrid.h
Update the widget SecondarySort without removing it and readding it again.
void UpdateWidget ( const [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SWidget](API\Runtime\SlateCore\Widgets\SWidget) > & InWidget, [FSlateInvalidationWidgetSortOrder](API\Runtime\SlateCore\FastUpdate\FSlateInvalidationWidgetSortOrde-) InSecondarySort )